1. Field of the Invention
The present invention relates to a data transmitting/receiving apparatus and a data communication system using a telephone network and, more particularly, to a data transmitting/receiving apparatus and a data communication system by which a common user can transmit message information including characters or consisting of characters to either a desired person or a desired place through the telephone network.
2. Description of the Related Art
As a data communication system using the telephone network, there are a radio paging system, a home banking system and the like. In these systems, a push-button telephone (hereinafter referred to as a "push-phone" or key telephone is a simple data transmitting apparatus which a common user can use easily. However, only ten numeric keys, i.e., 0 key to 9 key and two function keys, i.e., * key and # key are provided in the push-phone as operation keys so that only numeric data can be in principle transmitted by the push-phone. Therefore, when character data is transmitted from the push-phone, the key operations are performed in accordance with an agreement concluded between the transmitter side and the receiver side, in which each character corresponds to a different two-digit numeral combination, for example. When character data is actually input from the push-phone, the user must input numerals by key operation while referring to a predetermined matrix character arrangement table which stores the above agreement. As a result, a drawback that the inputting operation becomes troublesome occurs. Further, since the message is input by inputting numerals together with the telephone number or call number of the receiver side, it may become unclear to know the amount of numeral data which has been input in the course of the numeral inputting process. As a result, another drawback that numeral data tends to be erroneously input also occurs.
An auto-dialer can be used as an apparatus for simplifying the key operation of the push-phone. The auto-dialer outputs a tone corresponding to a DTMF (Dual Tone Multi-Frequency) signal which is a dial signal for the push-phone. Telephone number and so forth are in advance input by the operation of the numeric key and, when the user calls up on the telephone, the user couples the speaker of the auto-dialer which generates a tone of the DTMF signal to the transmitter of the handset of the push-phone to output the DTMF signal. Using the auto-dialer, the key operation of the push-phone can be extremely simplified. However, the above two drawbacks are not overcome when the telephone number and a message are set in the auto-dialer.